May 5, 2022 at 2:13 pm #704777
Help!! Multiple DTC’s!! 2001 5.3l Gmc Yukon XL SLT 1500 4wd w 190,000 mi
Originally Unable to get SMOG Cert due to SES MIL light illum. (or Inc. Cat Monitor)
Currently has P0101, P0155, P0300, & p0756 (after replacing ECM, Coils, Wires, & Plugs)
Previously had P0171 that wouldn’t go away ( the following has transpired over approx last 18 mo’s)
Initially the service engine soon light (MIL) came on found P0171 code.
Erased code, Cat Monitor won’t complete before another stored P0171 DTC illum’s MIL
B1 short fuel trim varied from -20 to +25 but typical was -5 to +5,
B1 long fuel trim rarely went below +25 and up to +40 at times
B2 short fuel trim avg. -2.5 to +2.5, long fuel trim avg -14.8 to +15,
Note; after each repair I would erase codes and do GM drive cycle. all monitors would Complete
except the Cat monitor then mil illum w p0171
since then have replaced the following:
O2 Sensors B1S1 & B1S2 (p0171 still)
New fuel pump & filter, Press 48 psi, pulse 39-40psi (p0171 still)
Vacuum leak test (no leaks detected)
New air fltr, Mass Air Flow Snsr, Battery, Pos & Neg Batt cables, Alternator, Cleaned all obvious Ground’s (p0171 still)
Smoke press. test intake, found very small intermittent wisps around intake #3 cyl
Replaced Intake manifold gaskets, (p0171 still) (Also new water pump, Radiator, Oil & Fltr,(unrelated to drivbility issues)
No codes but still Cat monitor won’t complete and after numerous drive cycles
and intermittent MIL (it would go off by itself) found intermittent p0171 usually pending
but stored when MIL stayed illum) also engine would intermittently sputter and hickup at higher revs on freeway with blinking then steady then no MIL (p0171 at times stored usually pending & sometimes P0300 pending, MIL intrmtntly on & off by itself other than that engine performance was pretty good with no MIL’s for days / weeks at a time. (still no Smog cert. Cat monitor doesn’t fail it just won’t complete. Then…..
Suddenly started running really rough, coughing, sputtering, no power, no throttle response, (no rpm’s except in P or N) or eventually (3-10 sec’s w thrtl deprssd) when manually placed in L1, upon manual shift to higher gear at higher rpm 3k-5k rpm drop and cough, and frequently stall when shifted even at higher revs.
MIL constantly Flashing or On steady. Found Numerous DTC’s Stored and Pending,
Lean Bank 1, Multiple/Random Cylinder Misfire, MAF out of Range, EGR oor, Shift Solenoid Malfunction, Throttle Position Sensor Error, O2 Sensor oor B1S2 & B2S2, Evap Rec. Systm Mlfnctn, VSS Error,
Removed ECM and after visual inspection (connectors and visible wiring, smell, etc…) Reinstalled.
Running like Shit after a minute or two, Idles fine but a little rough. Multiple DTC’s again
Decided at this point that the ECM must be faulty.
Replaced ECM w/ Remanufactured and Pre Programmed ECM (matched to orig VIN prgrming)
Engine crank but won’t run for more than .5 sec.
After sorting out V.A.S. issues (key relearn) engine starts & barely runs w blinking MIL. P0300 DTC
Replace Coils, Plugs, and Wires. Reset MIL, Starts and runs OK? within first mile (minute) starts sputtering. gets worse, within 2 miles (or approx 2-3mins) no throttle response (xcept in N or P), fuel light illum & gauge sporadicly goes to E then back to 1/4, but confirmed at least 1/4 tank, no power, seems to occur or get worse as engine warms up. cold start engine runs and drives OK? for about less than 5 min’s or under 2 miles
then it sputters and dies. ( ECT 205f) cranks but wont run with DTC’s P0101, P0155, P0300, P0756.
Starts and drives (when cold?) but not for very long or far.
Kinda at a loss here as far as what to check next? I’m thinking wiring, Grounding problem?
My scan tool is limited to OBDII emissions only so not really much help.
Any suggestions, advice, or Tech info will be greatly appreciated Thx Steve R. Santa Cruz Ca.
You must be logged in to reply to this topic.